On Thu, Jul 12, 2018 at 05:21:09PM -0500, Bjorn Helgaas wrote: > On Sat, Jun 16, 2018 at 09:25:00PM +0200, Lukas Wunner wrote: > > When pciehp is converted to threaded IRQ handling, removal of unplugged > > devices below a PCIe hotplug port happens synchronously in the IRQ > > thread. Removal of devices typically entails a call to free_irq() by > > their drivers. > > > > If those devices share their IRQ with the hotplug port, free_irq() > > deadlocks because it calls synchronize_irq() to wait for all hard IRQ > > handlers as well as all threads sharing the IRQ to finish. > > > > Actually it's sufficient to wait only for the IRQ thread of the removed > > device, so call synchronize_hardirq() to wait for all hard IRQ handlers > > to finish, but no longer for any threads. Compensate by rearranging the > > control flow in irq_wait_for_interrupt() such that the device's thread > > is allowed to run one last time after kthread_stop() has been called. > > I assume this would need to be merged along with the rest of the > series, which should probably go through the PCI tree, but I'm > definitely not qualified to review this IRQ patch. And it would need > an ack from Thomas in any case. A v2 of this patch has already been merged through the tip tree on June 24, it's in linux-next as commit 519cc8652b3a, and ISTR that I marked this patch either as "Obsoleted" or "Not Applicable" in pci-patchwork. There was no build-dependency of the succeeding patches in the series on this patch, hence merging through a different tree was possible. Thanks! Lukas
